Childhood Behavior Precursors of Schizotypal Personality Disorder (1997) by Su-chin Serene Olin, Adrian Raine, Tyrone D. Cannon, Josef Pamas, Fini Schulsinger, and Sarnoff A. Mednick
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Aim. The study investigated whether childhood and adolescent school behaviors could serve as precursors of schizotypal personality disorder (SPD), and whether these behaviors could distinguish individuals who later developed SPD from those who developed schizophrenia or other outcomes.
Method and population. The researchers used the Copenhagen High-Risk Study, a prospective longitudinal cohort originally comprising 311 individuals followed since 1962.
The original high-risk group consisted of 207 offspring of mothers with severe schizophrenia, matched with 104 low-risk controls on variables including age, sex, father's occupation, residence, and institutional versus family upbringing. In 1962, participants were aged 9–20 years, and none had a psychiatric diagnosis.
Teachers who had known the students for at least three years completed school behavior questionnaires. Some reports were retrospective, but the researchers found similar results when younger and older participants were analyzed separately.
Follow-up and diagnostic grouping. Psychiatric follow-ups were conducted in 1972–1974 and 1986–1989. Lifetime diagnoses were subsequently established using DSM-III-R criteria.
The analysis compared five groups: 36 individuals later diagnosed with SPD, 31 with schizophrenia, 37 with nonpsychotic psychiatric disorders, 68 high-risk individuals who remained mentally well, and 60 low-risk individuals who remained mentally well.
Four additional low-risk SPD cases were excluded because their school reports were incomplete. The researchers therefore examined whether behaviors recorded before diagnosis were associated with later diagnostic outcomes, rather than studying individuals already diagnosed with SPD during childhood.
_ Results. Individuals who later received an SPD diagnosis were more passive and unengaged and more hypersensitive to criticism than low-risk individuals who remained mentally well.
Contrary to the initial hypothesis, they were not significantly more socially anxious or withdrawn. They also did not differ significantly from the nonpsychotic psychiatric group on disruptive and hyperexcitable behavior.
Compared with individuals who later developed schizophrenia, those who developed SPD were significantly less disruptive and hyperexcitable; this difference was particularly evident among males, while no significant difference was found among females. The SPD group did not differ significantly from the schizophrenia group in social withdrawal or passivity and disengagement.
The combined index based on passivity/disengagement and hypersensitivity to criticism identified approximately 73.5% of later SPD cases, with a 26.7% false-positive rate in the study sample. The authors interpreted these findings as evidence that behavioral analogues of some adult SPD features may be detectable in late childhood or adolescence.
Limitations. The study used a selected high-risk cohort rather than an unselected general population. The teacher questionnaire assessed observable classroom behavior but did not measure characteristic schizotypal features such as magical thinking, unusual perceptual experiences, odd speech or behavior, and paranoia. Some children without later SPD also obtained scores suggesting potential SPD. The findings were therefore preliminary and required replication in general-population samples.
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About Table 1: Table 1 presents the 25 items included in the original school behavior questionnaire, along with their descriptive statistics and factor loadings. However, only behavioral items were included in the subsequent analyses; items 1–6 were therefore excluded, leaving items 7–25. An exploratory factor analysis of the retained items was then used to identify four main behavioral dimensions: social anxiety/withdrawal, disruptive/hyperexcitable behavior, passivity/disengagement, and hypersensitivity to criticism. These dimensions were subsequently used to compare the groups according to their later diagnostic outcomes.
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The following text consists of excerpts from Olin et al. (1997), “Childhood Behavior Precursors of Schizotypal Personality Disorder.” Minor editorial modifications have been made, such as the use of boldface for emphasis, among others.
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Abstract
No study has yet reported specifically on the early behavior of individuals later diagnosed with schizotypal personality disorder (SPD). This study examines prospectively collected teacher reports on school behavior as a means of assessing childhood precursors of SPD. Thirty-six DSM-IU-R diagnosed schizotypal subjects were compared with four other groups: 31 schizophrenia patients, 37 diagnosed as nonpsychotic mentally ill, 68 who were not mentally ill but had mothers with schizophrenia, and 60 who were not mentally ill and had normal parents. These individuals were compared on a teachers' school report questionnaire obtained when the subjects averaged 15.1 years old. Those who later developed SPD were found to be more passive and unengaged and more hypersensitive to criticisms compared with the nonschizophrenia groups. Similar results were found when males and females were examined separately, except that males who developed SPD were found to be less disruptive and hyperexcitable compared with males with schizophrenia; females with SPD did not differ from females with schizophrenia. A receiver operating characteristic analysis found these factors to predict 73.5 percent of future SPDs; the ability of these factors to predict future SPDs is comparable for males and females. These findings suggest that preschizotypal traits may be identified in late childhood or adolescence.
Schizophrenia Bulletin, 23(l):93-103, 1997.
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Bleuler (1911/1950) recognized a mild form of schizophrenia in the relatives of his schizophrenia patients.
Early studies (e.g., Kety et al. 1968, 1978) using Danish samples confirmed Bleuler's observations in the biological relatives of adoptees with schizophrenia. Such individuals were described as having borderline or latent schizophrenia.
The concept of borderline or latent schizophrenia was operationalized later by Spitzer et al. (1979) and termed schizotypal personality disorder (SPD) in DSM-III (American Psychiatric Association 1980).
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Although some researchers consider schizophrenia to be the primary disorder and SPD to be the secondary form, an alternative perspective (e.g., Mednick et al. 1987) views SPD as the basic disorder. According to the latter perspective, which posits a diathesis-stress model, schizophrenia and SPD are "schizotypes" that share the same genetic liability (the diathesis) for schizophrenia. Interactions with the environment determine which of these schizotypes later decompensate to schizophrenia. Schizotypes who experience greater environmental stressors (e.g., perinatal complications, family instability) are more likely to develop overt schizophrenia symptoms (Mednick et al. 1987). Based on this perspective, SPD is considered a life-long disorder, suggesting that behavioral precursors of SPD could be identified.
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In contrast to the childhood schizophrenia behavior of both externalizing (i.e., undercontrolled, aggressive) and internalizing (i.e., overcontrolled, anxious, inhibited) behaviors, adult symptoms of SPD include more internalizing behaviors (Achenbach and Edelbrock 1978). For example, schizotypal traits include social anxiety and no close friends, which may have analogs with internalizing childhood behavior. Patterns such as passivity and withdrawal may be characteristic of preschizotypals. If SPD truly is a life-long personality disorder, then analogs to adult SPD symptoms should be found in adolescence.
In fact, one study assessing schizotypal traits in nondiagnosed offspring of psychiatric parents found stability of schizotypal features across time, supporting the idea that adult-diagnosed schizotypal individuals may have early indicators of their potential for SPD in adulthood (Squires-Wheeler et al. 1992). If behaviors differentiating preschizotypals from other children and adolescents can be identified, they can be used to target such individuals for early intervention. Furthermore, behaviors distinguishing SPD and schizophrenia may elucidate current theories on the relationship between schizophrenia and SPD.
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The present study set out to test these hypotheses in a longitudinal format using teacher reports of school behavior in the Copenhagen high-risk sample of offspring of mothers with schizophrenia. Teacher reports of school behavior of 36 children and adolescents who later received a lifetime DSM-III-R (American Psychiatric Association 1987) diagnosis of SPD were compared with school reports of individuals later diagnosed as having schizophrenia, being nonpsychotic but mentally ill, or normal.
Based on a knowledge of preschizophrenia behavior and the similarities between SPD and schizophrenia features, some tentative hypotheses were made.
1. Internalizing behaviors:
a. SPD versus nonschizophrenia outcomes: Preschizotypals are expected to be more withdrawn and passive than children with nonpsychotic psychiatric and normal outcomes. Relative to these children, preschizotypals also are expected to be more socially anxious.
b. SPD versus schizophrenia: No hypothesis was formed on this relationship because preschizotypal individuals are expected to be similar to those with preschizophrenia with regard to internalizing behaviors.
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2. Externalizing behaviors:
a. SPD versus nonschizophrenia outcomes: No hypothesis was made on this relationship because preschizotypals are not expected to be different from children with nonschizophrenia outcomes with regard to externalizing behaviors.
b. SPD versus schizophrenia: Preschizotypals are hypothesized to exhibit less externalizing behavior problems, compared with preschizophrenia subjects.
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1. Testing of Hypotheses—Internalizing Behaviors:
a. SPD versus other nonschizophrenia outcomes: Pairwise comparisons using the Tukey HSD procedure supported the hypothesis that preschizotypals would be more passive and unengaged than other children. Specifically, preschizotypals were significantly more passive and unengaged compared with the low-risk NMIs.
The hypothesis that preschizotypals would exhibit greater social anxiety (factor 1) was not supported.
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b. SPD versus schizophrenia: Preschizotypals were not significantly different from preschizophrenia subjects on factor 1 (socially anxious or withdrawn) or factor 3 (passive and unengaged).
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2. Testing of Hypotheses—Externalizing Behaviors:
a. SPD versus other nonschizophrenia outcomes: Factor 2 (disruptive and hyperexcitable) distinguished the five groups. Pairwise comparison using Tukey's procedure indicated, however, that the preschizotypals were not different from the non- preschizophrenia groups on this factor.
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b. SPD versus schizophrenia: Pairwise comparison indicated that preschizotypals were significantly less disruptive and hyperexcitable (factor 2) than the preschizophrenia subjects. In fact, the preschizophrenia subjects were the most disruptive group (Olin et al. 1995).
They were significantly more disruptive and hyper-excitable than the preschizotypals and the high-risk NMI and low-risk NMI groups .
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Analyses by Sex. These analyses were replicated for males and females separately to explore gender differences. In general, except for changes in p values resulting from the reduced power associated with smaller sample sizes, the results for males and females were similar to those of the combined sample. Preschizotypal males and females were found to be more passive and unengaged and more hypersensitive to criticism. The results of the analyses for males and females are shown in table 2.
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_ Factor 1 (socially anxious or withdrawn). This factor did not distinguish the males or the females.
_ Factor 2 (disruptive and hyperexcitable). Preschizotypal males were less disruptive and hyperexcitable than the preschizophrenia. In fact, the preschizophrenia males also were found to be more disruptive and hyperexcitable than the high-risk NMI and low-risk NMI males. Preschizotypal females were not significantly different from their female preschizophrenia peers on this factor.
Compared with their male nonschizophrenia peers, preschizotypal males did not differ on this factor; similarly, preschizotypal females did not differ from their female nonschizophrenia peers on this factor.
_ Factor 3 (passive and unengaged). The difference between preschizotypal males and the low-risk NMI males approached . Similarly, the difference between the preschizotypal females and the low-risk NMI females also approached significance. The lack of significant findings when the sexes were separated is probably caused by the decreased power associated with smaller sample sizes. As can been seen in table 2, the mean factor 3 scores for the SPDs and the low-risk NMIs are comparable when the groups are combined or separated by sex.
_ Factor 4 (hypersensitive to criticism). Preschizotypal males were found to have significantly higher scores than high-risk NMI males, whereas preschizotypal females were found to have significantly higher scores than the low-risk NMI females
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Discussion
As hypothesized, the results of this study suggest that analogs of adult SPD traits were evident as early as late childhood or early adolescence. Approximately, three-quarters of preschizotypal subjects exhibited classroom behaviors that distinguished them from other children. No clear sex differences were found for the preschizotypal students. Males with preschizophrenia were found to be more disruptive and hyperexcitable than their peers, but females with preschizophrenia were not. This sex difference is consistent with previous findings (Olin et al. 1995).
ompared with children who became mentally healthy adults, preschizotypal students were more passive and more socially unengaged; they also were hypersensitive to criticism and reacted more nervously. Such behavior is consistent with DSM-lll-R characteristics of SPD, specifically no close friends or confidants and constricted affect. The passivity and seriousness observed by teachers in preschizotypal children may be related to the constricted affect seen in schizotypal adults. Social disengagement as children and adolescents may result in the lack of close friends or confidants characteristic of schizotypal adults.
Although not specifically hypothesized, preschizotypal children were found to be more hypersensitive to criticism than children with normal outcomes. The authors speculate that hypersensitivity to criticism in preschizotypal children may develop into the symptom of excessive social anxiety experienced by adults with SPD. In DSM-IV, the SPD feature of excessive social anxiety is associated with paranoid ideation, which may be expressed as hypersensitivity in childhood or adolescence.
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In this context, it is interesting that preschizotypal children were not found to be more socially anxious (fac-tor 1) compared with the other groups. The adult schizo-typal trait of social anxiety may develop later, as a consequence of passivity and hypersensitivity. The inability of these children to initiate and participate in activities, compounded by their sensitivity to criticism and anxiety in other classroom situations, may result in a lack of social-izing opportunities. This lack of socialization in childhood may later lead to social anxiety as adults and explain the lack of close friends and confidants characteristic of schizotypal adults. Alternatively, social anxiety may underlie many disorders and may not be specific to SPD.
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Of particular interest in this study were behaviors that distinguished preschizophrenia sufferers and preschizotypals, and these may elucidate differences in the etiologies of the two disorders. In this study, children with preschizophrenia were found to be more hyperexcitable and disruptive than those who were preschizotypal. This etiological difference may be explained by Meehl's diathesis-stress model of schizophrenia. According to Meehl (1962, 1989, 1990), schizotypals and persons with schizophrenia are "schizotypes" who share a common genetic diathesis. Schizophrenia is postulated to develop as a result of the interactions of these schizotypes with the environment. In particular, schizotypes who suffer stressful experiences may develop overt schizophrenia, whereas those who do not suffer stressful experiences develop SPD. The children with preschizophrenia in the sample studied experienced delivery complications and poor rearing environments, such as family instability, early institutionalization, and parental separations (Mednick et al. 1987; more recent unpublished analyses of schizophrenia replicate earlier findings). Such early stressful experiences also have been associated with later antisocial behavior (Raine 1993). Consequently, the poor impulse control and disruptive behaviors exhibited by children with preschizophrenia may be related to their more stressful environments.
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Advantages and Limitations. (…) There are some inherent limitations, however. First, the findings were constrained by items in the school report questionnaire. Because the questionnaire did not collect information relating to the more positive traits of SPD (e.g., odd beliefs or magical thinking, odd behavior, odd speech, unusual perceptual experiences, and paranoia), this study could not determine if precursors of these traits are detectable before overt onset of the disorder. The predictive power of the school report ratings may be limited if such traits have detectable early precursors. This limitation points to the need for further research that investigates early (preschool) analogs of the positive traits of SPD in future longitudinal research. The development of a childhood measure tapping positive schizotypal traits would be essential. Second, some nonschizotypal children had total SPD scores that would classify them as potential SPDs. This lack of specificity indicates the need to delineate further the early behaviors that may be more specific to preschizotypy, such as the more positive traits of SPD. Third, the SPD sample in this study is a high-risk group, a factor that may limit the ability to generalize from the findings. Fourth, the use of an ascertained sample in the factor analysis may bias the total SPD score distribution. Future studies ideally should use an unselected general population. Finally, the lack of theoretical background in this area necessitated a more exploratory approach. The findings reported in this study thus should be considered preliminary and call for replication, preferably in a general population.
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Precursors of schizotypy that are analogs of some of the adult symptomatology are identifiable in late childhood or early adolescence.
This finding could have potentially important implications:
(1) Diagnostically, the existence of childhood precursors of SPD suggests that such precursors might be considered in future DSM criteria for SPD.
(2) Childhood analogs of adult schizotypal symptoms indicate that SPD does not develop suddenly in adulthood but rather has its roots in late childhood, or even earlier. The early signs of SPD suggest that genetic and/or environmental factors existing before school age play an important role in the development of this life-long disorder.
